Sustainable photodegradation of pharmaceuticals: KOH-impregnated palm oil mill effluent sludge biochar-BiOBr nanocomposite for wastewater treatment

• Published in: Journal of alloys and compounds 2024-12, Vol.1007, p.176431, Article 176431
• Main Authors: Abdul-Raheem, Maryam Nike, Ahmad, Mohd Azmier, Yusop, Mohamad Firdaus Mohamad, Hassan, Oskar Hasdinor, Baidurah, Siti, Olajide, Olaoye Abdulmutolib, Adnan, Rohana, Sagadevan, Suresh, Kaus, Noor Haida Mohd
• Format: Article
• Language: English
• Subjects: BiOBr; Biochar; Ciprofloxacin; Photocatalysis; Photofunctional materials; POMES
• ISSN: 0925-8388
• DOI: 10.1016/j.jallcom.2024.176431

Biochar has explored in the search of a cost-effective and environmentally friendly photocatalyst for the efficient degradation of CIP antibiotic pollutants. Biochar (BC) produced from palm oil mill sludge was used as a base to fabricate biochar-based BiOBr composites by varying the mass ratio of biochar and BiOBr via a hydrothermal route. The optimized composites BBC-1:1 has exhibited the formation of crystal struvture as tetragonal BiOBr with a a significant specific surface of 267 m2/g (BBC-1:1) while incorporating different mass ratios of BC with BiOBr. This composite facilitates the band gap of BiOBr from 2.87 to 2.42 eV and is consistent with the decreasing recombination rate of electron-hole pairs as suggested by UV-Vis DRS and photoluminescence (PL), respectively. Consequently, the synergistic effect of biochar BiOBr leads to a higher degradation efficiency of CIP showing the highest efficiency (97.49 %) and that of pure BiOBr being 55.66 % under optimized conditions. The degradation rate of the BBC-1:1 composite which observed to be 0.0156 min−1 is 3.25 times that of BiOBr (0.0048 min−1). Furthermore, the scavenging experiments confirmed the significant contribution of the active radicals h+ and O2- as the main photoactive species in the photocatalytic degradation of CIP. Consequently, the photocatalytic degradation mechanism was discussed and the reusability test confirmed the high stability of the BBC composites up to 77 % for the seventh cycles. These results show that the BBC composite is suitable for large-scale practical applications as a green photocatalyst. [Display omitted] •Production of POMES biochar via pyrolysis for enhancing photocatalytic activity was described.•The surface area of the prepared POMES biochar-based (267 m2/g) photocatalyst is higher than the pristine BiOBr (2.85 m2/g).•POMES biochar significantly reduced the band gap of BiOBr from 2.87 – 2.42 eV.•POMES biochar played a key role in improving the degradation efficiency of CIP from ∼ 55–97 %.•Possible interaction mechanisms between the biochar-based photocatalyst composites and Ciprofloxacin was established.